Definition
Cancer is the uncontrolled growth of abnormal cells in the body. Cancerous cells are also called malignant cells.
Alternative Names
Carcinoma; Malignant tumor
Causes, incidence, and risk factors
Cells are the building blocks of living things. Cancer grows out of normal cells in the body. Normal cells multiply when the body needs them, and die when the body doesn't need them. Cancer appears to occur when the growth of cells in the body is out of control and cells divide too quickly. It can also occur when cells “forget” how to die.
There are many different kinds of cancers. Cancer can develop in almost any organ or tissue, such as the lung, colon, breast, skin, bones, or nerve tissue.
There are many causes of cancers, including:
- Benzene and other chemicals
- Certain poisonous mushrooms and a type of poison that can grow on peanut plants (aflatoxins)
- Certain viruses
- Radiation
- Sunlight
- Tobacco
However, the cause of many cancers remains unknown.
The most common cause of cancer-related death is lung cancer.
The three most common cancers in men in the United States are:
In women in the U.S., the three most common cancers are:
Some cancers are more common in certain parts of the world. For example, in Japan, there are many cases of gastric cancer, but in the U.S. this type of cancer is pretty rare. Differences in diet may play a role.
Some other types of cancers include:
Symptoms
Symptoms of cancer depend on the type and location of the tumor.
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